Thermal inkjet printers typically have a printhead for generating ink drops and ejecting them onto a printing medium. The typical inkjet printhead includes: a nozzle plate having an array of orifices that face the paper; ink channels for supplying ink from an ink source, such as a reservoir, to the orifices; and a substrate carrying a plurality of heating resistors, each resistor positioned below a corresponding orifice. Current pulses are applied to the heating resistors to momentarily vaporize the ink in the ink channels into bubbles. The ink droplets are expelled from each orifice by the growth and subsequent collapse of the bubbles. As ink in the ink channels is expelled as droplets through the nozzles, more ink fills the ink channels from the reservoir.
The objects and features of the present invention will be better understood when considered in connection with the accompany drawings. Note that the drawings are schematic, unscaled illustrations and like reference numbers designate like parts throughout.